Voltage Measurement Tutorial

Electricity is very hard to imagine because we can not see if a voltage is present or if a current is flowing. If we want water to flow out of a pipe we need some water pressure which is achieved with a water pump. In electricity, our flow is the current, water pressure is the voltage and pump is the battery. This means that the voltage is the cause of the current.

Electricity is very hard to imagine because we can not see if a voltage is present or if a current is flowing, so let us try to explain electricity with water analogy. Water systems or circuits are simple to understand because we can see water and it’s the one thing we are used to. Now let’s see how the water system works. We all know if we want water to flow out of a pipe we need some water pressure which is achieved with a water pump. In electricity, our flow is the current, water pressure is the voltage and pump is the battery. This means that the voltage is the cause of the current like the water pressure is the cause of volume flowrate of water.

A measurement device for measuring the voltage is called a voltmeter. To measure the voltage, otherwise known as the potential difference between two points, the voltmeter is always connected in parallel to the circuit (see picture). To influence the circuit as little as possible, the input impedance of the voltmeter has to be very high. The typical input impedance of Voltmeter is 10 MΩ.

Measuring voltage is the most basic measurement with DAQ devices because most of the AD converters use voltage as the input value. That’s why measuring voltage with DAQ seems simple, right? The answer is yes if we are measuring voltages in the range that is directly supported by the AD converter. But when measuring very small voltages of some micro-Volts (µV) or very high voltages up to several kilo-Volts (kV), an amplifier is needed to prepare the signal for the AD conversion. For both challenges Dewesoft has the right solution.

On one hand the Low Voltage amplifier (LV and HS-LV) together with the 24-bit ADC technology allows measurements of very low voltages also at high measurement ranges (e.g. µV resolution at a range of ± 10V).

On the other hand, the High Voltage amplifier (HV and HS-HV) allows to directly measure voltages up to 1600V DC (1200V DC at HS-module). For measuring voltages higher than 1600 VDC, voltage probes/dividers or voltage transducers can be connected to the device.